Friday 24 April 2020

REPAIR / SERVICING TV SHIVAKI STV-26L2

Technical description and composition of the TV SHIVAKI STV-26L2, type of panel and applicable modules. The composition of the modules.
SHIVAKI
Model: STV-26L2
Panel: SHFA060297641
Inverter (backlight): VT71008.90 Logah REV: 0
PWM Inverter: LM339A, LM393
MOSFET Inverter: 4612
Power Supply (PSU): MLT070A
PWM Power: ML4800CS, FAN7601, LM358
MOSFET Power: 20N60, 9N50, 5N60
MainBoard: PA-0157-1TG LM21C UOC3
IC MainBoard: MST6151A, TDA12063H, AN17820N, K4S161622H-UC60,
Tuner: TDQ6F6T1260
Technical Specifications STV-26L2
SHIVAKI STV-26L2
General recommendations for repairing TV LCD
It is advisable to start the diagnostics of a malfunction of the SHIVAKI STV-26L2 KALININGRAD TV, like all others, with an external examination of possible changes, both external and internal elements. Any external damage can sometimes prompt the repairman to take further steps to determine the malfunction of the TV and localize the defect. Swollen electrolytic or cermet capacitors, charred resistors, ring cracks in the soldered terminals of the elements - all this can significantly help the master to determine the causes and consequences of the malfunction of the TV.
Malfunctions of the MLT070A power supply module can be expressed in different ways, for example, SHIVAKI STV-26L2 KALININGRAD does not turn on at all and the control lamps on its front panel do not light up and do not blink, there are no signs of operability. When diagnosing and repairing the power supply, first of all, it is necessary to check the fuse and, if it is broken, it is necessary to identify the cause. Often in such cases, an avalanche (thermal) breakdown is detected in the power semiconductor elements of the module — rectifier diodes or power switch 20N60, 9N50, 5N60.
It should be remembered that the N-FET keys used in flyback converters rarely fail for no reason that must be sought by checking other elements of the circuit. Often the breakdown is caused by malfunctions of electrolytic capacitors or semiconductor elements in the primary circuit, or by a break in the resistors in the stabilization circuits. The PWM controller chip ML4800C6, LM358, 20N60 can also cause a breakdown of the power switch of the converter.
It is somewhat more difficult to look for a malfunction in the converter of the power module with an active KKM (power factor corrector).
If the SHIVAKI STV-26L2 KALININGRAD does not have an image, but there is sound and the TV is controlled from the remote control, a malfunction in the display backlight nodes is likely. The lamps or the power converter - inverter may be faulty. Often in such cases, when you turn on the TV, an image appears and immediately disappears. First of all, it is necessary to verify the operability of the electrolytic capacitors of the rectifier filter supplying the inverter, and check the LCD lamps by connecting external and obviously serviceable for diagnosis to the connectors.
In most cases, the diagnosis and repair of the VT71008.90 Logah REV: 0 inverter is difficult due to the organization of protection, which turns it off in emergency cases to avoid fires during short circuits or open circuits in high voltage circuits and during lamp depressurization. Often, repairmen block the protection circuits in order to make the necessary measurements at the inverter control points to identify the causes of the defect.
All necessary precautions must be observed when disabling the inverter protection during diagnostics and not leaving it disconnected after the repair is completed.
On the tun TDQ6F6T1260 motherboard, in case of a malfunction, you should first check the operation of all power supply stabilizers of the microcircuits and, if necessary, update the software (software). Often, the MB (SSB) card must be replaced in case of complex malfunctions that are difficult to detect. When trying to repair, you should check its elements - MST6151A, TDA12063H, AN17820N, K4S161622H-UC60, and replace failed chips with new ones.
Owners and users of the SHIVAKI STV-26L2 KALININGRAD TV must remember that self-repair without special knowledge, skills and qualifications can be fraught with negative consequences, which can lead to complete non-repairability of the device!
Repair MainBoard
The appearance of MainBoard PA-0157-1TG is shown in the figure below:
PA-0157-1TG
PA-0157-1TG can be used in TVs:
SHIVAKI LCD-2610DVD (Panel 26 inches), SHIVAKI STV-26L2 (Panel SHFA060297641).
The appearance of the power supply
Main features of the SHIVAKI STV-26L2 device:
Installed matrix (LCD panel) SHFA060297641.
To power the backlight, an inverter VT71008.90 is used, it is controlled by the PWM controller LM339A, LM393. As power elements of the inverter, keys of type 4612 are used.
The necessary supply voltages for all nodes of the SHIVAKI STV-26L2 TV are generated by the MLT070A power supply module or its analogs using ML4800CS, FAN7601, LM358 microcircuits and power switches of the type 20N60, 9N50, 5N60.
MainBoard - the main board (motherboard) is a module PA-0157-1TG, using chips MST6151A, TDA12063H, AN17820N, K4S161622H-UC60, and others.
The TDQ6F6T1260 tuner provides TV reception and channel tuning.

TV SHIVAKI STV-26L2 with LCD SHFA060297641, diagonal size 26 "(66 cm) 16: 9 format. The brightness of the screen is 500 cd / m² backlight fluorescent lamps CCFL (EEFL). Contrast, as the ratio of maximum brightness to minimum, is 800: 1. It is possible to view images in high quality HD at a resolution of 1366x768 pixels in the standard for graphic decomposition 720p (HD Ready). The input high-frequency or video signal can be processed in analog systems PAL, SECAM, NTSC. Graphic processing and digital signal generation takes place in st Andartach 480i, 480p, 576i, 576p, 720p, 1080i. Stereo sound is realized by two built-in speakers. The audio processing system NICAM STEREO is used.
The external interface (communication with other devices) is supported by standard input and output connectors: antenna input (RF), AV, S-Video, component, SCART, RGB, VGA, DVI HDCP. To connect a computer or laptop to this TV model, a VGA (D-Sub 15) connector is used on the TV case, this interface supports resolutions: 640x480, 800x600, 1024x768, 1280x1024, 1360x768.
Dimensions: With stand 798x626x226 mm, Without stand 581x371x43 mm.
Attention! The SHFAAK6060297641 panel of the SHIVAKI STV-26L2 LCD TV is its most expensive component.
Avoid hitting the glass and exerting pressure on the screen to avoid permanent damage to the LCD panel!